This is an application for one-year financial support to plan several interrelated epidemiologic research projects in dry eye under the title Dry Eye Epidemiologic Projects (DEEP). Little is known about the prevalence or about other epidemiologic features of dry eye, a common condition accounting for a large percentage of visits to ophthalmologists in the United States. In DEEP, persons with dry eye aged 25-79 will be divided into four categories: Sjogren's syndrome, non-Sjogren aqueous- deficient dry eye, blepharitis, and non-blepharitis aqueous adequate dry eye. DEEP's aims are to estimate age-sex-race-specific disease prevalence in a probability sample of the general population, and, with persons from that sample as subjects, to conduct longitudinal and case-control studies to investigate clinical course, prognosis, and risk factors for dry eye. A sample of 100 Sjogren's syndrome patients from four clinics will supplement the longitudinal and case-control studies of Sjogren's syndrome from the general population sample. The prevalence survey will start with a screening interview, and finish with a clinical examination of all positive screenees and of a sample of negative screenees. The aims of the longitudinal studies, which will include a quality-of-life component, are to investigate whether the dry eye condition improves or gets worse with time, and whether patients with non-Sjogren's aqueous-adequate dry eye are at high risk of developing Sjogren's syndrome. The aims of the case- control studies, in which persons without dry eye will see as controls, are to investigate co-morbidity, hormonal factors, and sociodemographic and psychosocial variables as risk factors for dry eye. The aims of the planning phase are to explore the cost-effectiveness of several methods of selecting a probability sample of the population to be surveyed develop and pretest a screening questionnaire, convene a multidisciplinary group of experts to advise on the design of DEEP, recruit clinical centers for the studies of Sjogren's syndrome, recruit a serum laboratory and an impression cytology reading center, and write manuals of procedure for DEEP.